Process for cleaning iron ores.



y .23g/W E. F. GOLTRA.

PROGESS POR CLEANING IRoN'oRBs.

APPLICATION FILED IANA. 1910.

Patented May 3, 1910.

EDWARD r. ecrans, or sr. Louis, mssonnr.

PROCESS FOR CLEANING IRON CRES.

Specication of Lettere Patent.

Parenteel May a, reno.

Application filed January 4, 1910. Serial No. 536,403.

To all 'whom tt 'may concern.'

iBe it known that I, EDWARD F. Gorman, a citizen of the United States, and resident of St. Louis, State of Missouri,fhave invented certain new and useful Im rovements in .Processes for Cleaning Iron res, of which the following is a specification.

This invention relates to a process for cleaning iron ores and for preparing the same for the subsequent operations.

Some iron ores, as brown hematite, contain a large percentage of clay as a gangue, and this gangue must be separated from the ore before it can be used in the blast furnace. Heretofore the gangue in clayey ores has been separated from the ore by washing with water in the usual jigging or log washing operations. The ore and lits gangue were also thrown on an inclined sidewise movable screen, or in a revolving screen or trommel land subjected to a spray of water, which washed out the dirt. The above washing processes are; however, open to many objections. The stream of water carries olf much of the ore, and it is impossible to thoroughly clean the ore in this manner of all the gangue'in the crevices and in and around the ore. In some ores the percentage of clay is very high; sometimes there is from five to seven times as much clay as ore. It will, therefore, be readily seen that in order to Wash o ut this enormous quantity of clay by a stream of water, it will not only require enormous quantitiesof water, which is quite an item where water is scarce, but that these large quantities of water will carry with them a large percentage of the ore.

The ore, after being washed with water, must be dried and calcined before it can be used in the blast furnace. There are thus great losses of ore, heat in drying the wet ore, and in water, and even then the ore contains a large percentage of gangue. Due to the above objections to prior processes, it has been impossible and uneconomical to use large quantities of existing ores.

One of the objects of this invention, therefore, is to devise a process whereby the ore is washed or cleaned of its gangue by a blast of air, and another object is to devise a rocess' whereby the moisture and other vo atile matter are driven off and the ore prepared for the blast furnace. l

The invention generally stated consists in the operations as hereinafter fully described and claimed.

The process, and the a aratus for carr mg out the process. willp be described 1n connection with the accompanying drawings in which- Figure 1 is a section through a common form of roasting or calcining kiln, and 2 1s an elevation of a tumbling apparatus.

' Fig. 1, shows a common form of calcining kiln known as the Gjers calcining kiln.

It is a circular kiln, the walls 10 of which are built of iron plates lined with fire brick, the lower part being conical in form. The walls rest upon a cast iron ring 11 which is supported by cast iron columns 12, leaving a clear space for the removal of the calcined ore. A cast viron cone 13 with its apex upward rests on the foundation in the center of the kiln, directs the descending ore outward, and renders its removal more easy through the clear spaces between the columns. The walls are provided with a series of openings 14 sup lied with doors for the admission and regu ation of the air. The ore is added at the top and removed at the bottom as calcined so that the rocess is continuous. Since this calcining iln is of well known construction, further detailed description will be unnecessary.

Referring to Fig. 2, which shows a tumbling apparatus, 15 designates a tumbling barrel provided with a smooth ring 16 lresting upon anti-friction rollers '17, and a toothed ring 18' resting upon and meshing `with pinions 19. This tumbling barrel is provided with hollow cylindrical extensions 20 and 21 extending into and making an airtight connection with heads 22 and 23 respectively. The tumbling barrel or drum 15 is provided with .manholes which are closed by removable manhole covers 24C. A double hopper 25 is located above the tumbling barrel and supported by suitable framework so that when the tumbling barrel is moved to the position shown in Fig. 2, and the manhole covers 24' removed, the hopper will discharge into the barrel. The pinions 19 are driven by any suitable means, in this particular instance, one of the p-inion shafts 1s provided with a belt pulley 26, by means of which it may be belted to any suitable motor. A centrifugal fan or blower 27 is connected to the head 23, while the other head 22 is provided with a suitable intake ipe 28. By means of this fan a stronglast may be passed through the tumbling barrel while 1t is rotated around vits axis, the blast entering the intake 28 which is to be used in performing the process., the process will now be described.

The ore as mined is 1preferably crushed or reduced to a workab e form. 1t is not l'necessary to pulverize the ore, in fact itis preferable not to do so, but it is'sucientif 1t is crushed so it may ass through a two or two and one half inc mesh, or even to a larger size. 1n some cases it may not be necessary to crush the ore at all. The ore and its gangue when crushed, or in the condition as they leave the mine are charged in at the toA of the kiln shown in Fig. 1 and there su jected to a heating and calcining operation at a temperature and for a perio sucient so as to thorou hly dry out the^clayey gangue, and prefery so as to alsodrive od the free moisture, combined moisture if present and other volatile matter in order to prepare the ore for the furnace.

o The temperatures and the duration of the heating operation will, of course, depend upon the condition of the ore as to the amount of gangue and volatile matter contained therein etc. In all cases, however, the operation is continued until the gangue has been thoroughly dried out and rendered brittle. The heat will not only render the clayey'gangue brittle but 'any hard stone contained in the ore will also be separated. This stone gangue will sometimes occur in the ore in the form of layers; now the heat during the heating and calcining operations will cause the ore and stone to expand at diHerent rates and thus the stone will be broken and cracked 0H. A skilled operator can of course ascertain when the ore and .gangue have been reduced to the proper contumbling `,barrel through the manholes.

After a suilicient quantity of the ore and its gangue have been discharged into the tumbling barrel, the manhole covers are replaced and the tumblin barrel is started in operation. During t e revolving action of the tumbling barrel the ore and its gangue will be thrown around and tumbled so as to thoroughly shake loose the gangue from the y esalta'V ore. As this tumblin action proceeds and the gangue is knocke oli", the heavy lumps y during the 'tumbling operation, where the angue is shaken loose and pulverized. During the tumbling operation a strong blast is passed through the tumbling barrel and through the ore contained therein by means -of the fan 27. This blast in passing over,

through and around the ore as it is thrown around in the tumbling barrel, will sweep and clean the ore of its gangue. The blast will seek out the dried out and loosened ganguein, around and clinging to the ore and in the crevices and carry the gangue along with it leaving the heavier ore lumps in the' tumbling barrel. It will thus be seen 'that the blast of air washes the ore of its angue in the-same manner that the water oes in the' Water washing operation. 1n this process, however, the blast of air can enter crevices in the ore where a stream of water cannot enter, and thus practically all of the gangue will be washed out. After the ore has been washed of its gan e the blast is stop ed and the cleaned an washed ore is disc arged into the car 29.

The cleaned ore as it leaves the tumbling barrel is in a condition to be used in a blast furnace immediately and no preliminary calcining is necessary. The water and other volatile matter have been driven ed inthe heating and calcining operation, and the ore is laced in a porous condition, which is deslrabley for blast furnace operation. rlhis process, therefore, dispenses with all water 7 washing operations and its resultant losses in ore, heat, etc. and at the same time the ore is discharged after the air washing operation in a condition to be immediately used in the furnace.

In the specific embodiment of this apparatus, certain types of apparatus have been selected for convenience. It is to be understood, however, that this invention is vnot to be limited to the yspecific apparatus shown.

Any other type of apparatus may be used for heating and calcining the ore so as to render the gangue easily separable there# from, and any other apparatus may be used for tumbling the ore and cleaning it by the air blast. The tumblin apparatus may consist of a long inclin rotary drum or tube in which the prepared ore and gangue are fed in at one end while a blast passes through the drum in the opposite direction, the cleaned ore being discharged at the lower end. 1n all forms of apparatus, however, the essentials are that the ore be prepared for loosening the gangue and that the prepared gangue be Washed from the ore by the air blast.

In the specific apparatus shown, the heating and calcining apparatus and the tumbling apparatus are shown as separated and no connection is shown between them, the

prepared ore being conveyed to the tuinand Washing it from the ore. This particular embodiment is described in my cepending application Serial No. 523,091, tiled October 18,` 1909. All of these embodiments are Within the scope of this invention; it, therefore, is to be understood that this invention is not to be limited to the specific arrangement as shown and described.

Having thus described my invention, what I claim and desire to secure by Letters Fatent is 1. The herein described process of treating iron ores containing moist clay etc. as a gangue, which consists in heating the ore and its gangue at a temperature and for a period sulicicnt to drive ott the moisture and to render the gangue easily separable from the ore, tumbling the ore and its gangue to shake loose the gangue from thel ore and to pulverize the gangue by said tumbling action, and subjecting the ore and gangueto a strong gaseous blast which sweeps, cleans and removes (he gangue from the ore.

2. The herein described process of treating iron ores containing moist clay etc.,as a gangue, which consists in calcining the lumps of ore and its gangue at a temperature and for a period suflicient to expose and dry out the gangue and to render it easily separable from the ore7 to drive ott' the moisture and volatile matter, tumbling the ore and its gangue to shake loose the gangue from the ore and to pulver-izo the' gangue by said tumbling actionl ot* the lumps, and subjecting theore and vgangue `1o a strong gaseous blast which sweeps, cleans4 and removes the gangue from the ore.

In testimony whereof I aiix my signature in presence of two Witnesses.

EDWARD r. GoLrnA.

Witnesses:

J. D.. DANA, FRANK LUCAS. 

